I have many problems with this. Most prominent is the issue with icons on my primary display. I have many icons on my desktop and use them frequently. When I close the screen, the external display "squishes" my icons and when my laptop is re-opened, the "squished" icons do not reset. If I want to watch a movie by dragging a media player onto the secondary display, I cannot close my laptop as it will switch to the primary.
What I'd like to know is how I might be able to lock my primary display and not have the secondary screen switch without having to change a setting every time (like disabling the second before closing the laptop). My graphics card is an ATI Radeon X1300.